Scientists in China have developed a material that reduces the time required for a skin wound to heal.

A range of research has been conducted into the promising biomedical applications of chitosan, as it can clot blood effectively. Bingan Lu and his colleagues at Lanzhou University have developed a method to combine the benefits of chitosan with graphene, which has been shown to have antibacterial properties. 

Lu’s team mixed graphene with chitosan-polyvinyl alcohol (PVA) nanofibres using electrospinning (a process in which an electrical charge is applied to draw very fine fibres from the solution). The chitosan nanofibres combined with the graphene, forming thin membranes. 

The team applied the membranes to small skin wounds. Lu says that the membranes ‘covered the wounds like a band aid and, usually, one wound only needed one graphene-chitosan-PVA membrane’. They found that after 10 days, the wounds were significantly more healed than those without the membrane. 

A membrane formed from chitosan, which clots blood effectively, and graphene, which is antibacterial, speeds up wound healing

Chunhai Fan, an expert in graphene materials at the Chinese Academy of Sciences, says that the work ‘shows a really interesting health application of graphene-based nanomaterials’ and adds that it ‘clearly shows that graphene-based antibacterial materials facilitate wound healing’.

To test the membrane further, Lu’s team used cell cultures to show that graphene is only detrimental to bacterial cells, and animal cells are unaffected. They suggest that this may be due to graphene transferring electrons through cell membranes. Bacterial cells are prevented from replicating by this process, as the electrons can reach the bacterial DNA, destroying it. Animal DNA is protected from the electrons by a second membrane. The team intends to investigate graphene’s antibacterial properties to confirm the mechanism.

Graphene-based composite materials beneficial to wound healing
Bingan Lu, Ting Li, Haitao Zhao, Xiaodong Li, Caitian Gao, Shengxiang Zhang and Erqing Xie
DOI: 10.1039/C2NR11958G

Read the original article at Chemistry World

With the development of modern industries, heavy metal pollution in humans is on the rise, say researchers in China, who have now designed a supermagnetic nanocomposite to effectively remove one of the pollutants – cadmium ions – from blood.

The nanocomposite binds to cadmium ions in the blood and a magnet is used to attract the resulting complex for removal

Cadmium ions damage organs and are carcinogenic. Materials currently being studied to clear them from human blood don’t possess all the required properties for this purpose.

They either have good selectivity, high saturation magnetisation or good water dispersibility, but not all three. The new composite, made by Jun Jin and Jiantai Ma from Lanzhou University and colleagues, combines all of these properties.

The team built up the nanocomposite – PAD-PEG-Fe₃O₄@PEI – from four components. The first was magnetic iron oxide nanoparticles, chosen for their low toxicity. The team coated them with polyethylenimine (PEI), which binds to cadmium ions. The coating also reduces the chances of nanoparticle uptake by red blood cells, maximising their circulation time in the blood. Polyethylene glycol (PEG) was grafted onto this as an anchor for negatively charged 2,2′-(phenylazanediyl) diacetic acid (PAD), which counteracts interactions between the nanoparticles and plasma proteins or white blood cells.

Interested to know more? Read the full article in Chemistry World here…

 Read the paper from Nanoscale:

2, 2′-(phenylazanediyl) diacetic acid modified Fe₃O₄@PEI for selective removal of cadmium ions from blood
Jun Jin, Fang Yang, Fengwei Zhang, Wuquan Hu, Shao-bo Sun and Jiantai Ma
Nanoscale, 2012, Advance Article
DOI: 10.1039/C2NR11481J

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Scientists in Australia have found that mesoporous silica nanoparticles (MSNs) can store and deliver biocides in a controlled fashion over time, which could be beneficial to the timber industry with regards to termites.

Termites pose a significant threat to the industry throughout the tropics and subtropics. The conventional solution to this problem is to use agrochemical biocides such as dichloro-diphenyl-trichloroethane (DDT), aldrin, dieldrin, chlordane and heptachlor.

But these compounds cause environmental damage via bioaccumulation, threatening the existence of some species, particularly large predators at the top of the food chain. And attempts to destroy entire terminte colonies using them have been unsucessful. 

Now, Zhang Qiao and colleagues at the University of Queensland, have used the pore structure of mesoporous silica nanoparticles to adsorb biocides. They found that the nanoparticles released the biocide in a controlled manner. This slow release is important as the termintes will feed on and transfer the particles to other termites, eventually leading to colony destruction. 

The team chose four different types of MSN to test, using the agricultural biocide imidacloprid as a model. They found that MCM-48 particles had the highest adsorption capacity. ‘We can effectively load the biocide into MSNs and release it over 48 hours,’ says Qiao. ‘However, it is difficult to control the release because of the biocide’s water solubility and fast mass transport.’ 

Andrea O’Connor, an expert in nano and biomolecular engineering at the University of Melbourne, Australia, agrees that more control over release rates is needed. This would ‘minimise the early burst release and extend biocide delivery over biologically relevant time periods and dose rates’, she says. However, she adds that the system is simple and delivers the nanoparticles in a suspension into the site of an infestation ‘rather than relying on diffusion of released biocide through the environment, where it may be degraded or have undesirable adverse effects.’ 

Qiao adds that to effectively deliver the biocide over a period of about seven days, the MSNs need to be coated with other chemicals. The team is investigating a biodegradable polymer coating. 

Carl Saxton – Chemistry World 

Read the paper from Nanoscale: 

Adsorption and release of biocides with mesoporous silica nanoparticles
Amirali Popat, Jian Liu, Qiuhong Hu, Michael Kennedy, Brenton Peters, Gao Qing (Max) Lu and Shi Zhang Qiao
Nanoscale, 2012, Advance Article
DOI: 10.1039/C2NR11691J 

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Carbon nanotubes can enhance plant growth without damaging plant cells, say scientists from India

Sabyasachi Sarkar and colleagues from the Indian Institute of Technology in Kanpur treated chickpea plants with up to 6ug/ml of water soluble carbon nanotubes. They found that the nanotubes increased the growth rate in every part of the plant – in the roots, shoots and branches.

Sarkar thought that the channels could be replicated by carbon nanotubes. ‘We followed Thomas Edison’s recipe to make carbonised filament from bamboo or wood wool in his electric bulb to get the carbon nanotubes,‘ he adds. ‘Of course, we had to derivatise them to make them water soluble.’ The team achieved this by attaching carboxylic acid groups to the surface of the tubes.

‘The work seems to support the positive effect of carbon nanotubes,’ says Xiaohong Fang, an expert in the use of carbon nanotubes as molecular transporters in plants at the Chinese Academy of Sciences in China. However, she points out that the biological effects on plants may differ depending on the materials’ chemical and physical properties, plant type and cultivation conditions.

Read the rest of the Chemistry World story by Elinor Richards

View the Nanoscale article in full:

Growth stimulation of gram (Cicer arietinum) plant by water soluble carbon nanotubes
Shweta Tripathi, Sumit Kumar Sonkar and Sabyasachi Sarkar
Nanoscale, 2011, DOI: 10.1039/c0nr00722f